Practical machinery vibration analysis and predictive maintenance

1 Predictive maintenance techniques: Part 1 Predictive maintenance basics .......1 1.1 Maintenance philosophies ......................................................................1 1.2 Evolution of maintenance philosophies ...................................................4 1.3 Plant machinery classification and recommendations .............................5 1.4 Principles of predictive maintenance ......................................................6 1.5 Predictive maintenance techniques ........................................................7 1.6 Vibration analysis – a key predictive maintenance technique ..................8 2 Predictive maintenance techniques: Part 2 Vibration basics ............................11 2.1 Spring-mass system: mass, stiffness, damping .....................................11 2.2 System response ...................................................................................12 2.3 What is vibration? ..................................................................................13 2.4 The nature of vibration ...........................................................................14 2.5 Harmonics .............................................................................................18 2.6 Limits and standards of vibration ...........................................................23 3 Data acquisition ..................................................................................................29 3.1 Introduction ............................................................................................29 3.2 Collection of vibration signal – vibration transducers, characteristics and mountings ................................................................29 3.3 Conversion of vibrations to electrical signal ...........................................39 3.4 Conclusion .............................................................................................54 4 Signal processing, applications and representations ..........................................55 4.1 The fast Fourier transform (FFT) analysis .............................................55 4.2 Time waveform analysis ........................................................................64 4.3 Phase signal analysis ............................................................................67 4.4 Special signal processes .......................................................................69 4.5 Conclusion .............................................................................................88 5 Machinery fault diagnosis using vibration analysis .............................................89 5.1 Introduction ............................................................................................89 5.2 Commonly witnessed machinery faults diagnosed by vibration analysis................................................................................89 vi Contents 6 Correcting faults that cause vibration ............................................................... 134 6.1 Introduction ......................................................................................... 134 6.2 Balancing ............................................................................................ 134 6.3 Alignment............................................................................................. 145 6.4 Resonance vibration control with dynamic absorbers ......................... 164 7 Oil and particle analysis .…..….......……….......…......……..….......…...........…. 168 7.1 Introduction ......................................................................................... 168 7.2 Oil fundamentals ................................................................................. 169 7.3 Condition-based maintenance and oil analysis ................................... 172 7.4 Setting up an oil analysis program ...................................................... 175 7.5 Oil analysis – sampling methods ......................................................... 179 7.6 Oil analysis – lubricant properties ....................................................... 189 7.7 Oil analysis – contaminants in lubricants ............................................ 196 7.8 Particle analysis techniques ................................................................ 201 7.9 Alarm limits for various machines (source: National Tribology Services) ............................................................................................. 219 7.10 Conclusion ...……...............…..........……................……................……220 8 Other predictive maintenance techniques ...……...............…..........……........... 221 8.1 Introduction ........................................................................................ 221 8.2 Ultrasound .......................................................................................... 221 8.3 Infrared thermography ........................................................................ 229 8.4 Conclusion .......................................................................................... 234